224 THE CEPHALOPHORA. $ 201. 
Faminy: Sacirrina. 
Genus: Sagitta. , 
Famity Hyaeacea. 
Genera: Hyalea, Cleodora, Cymbulia, Tiedemannia, Cuvieria, Creseis, 
*  Limacina. 
Famity: Ciiorea. 
Genera: Clio, Pneumodermon, Spongiobranchaed. 
ORDER II. HETEROPODA. 
Animals whose locomotion is performed by a carinated natatory appara- 
tus situated under the abdomen and provided often with a sucker. 
Genera: Phyllirrhoé, Pterotrachea, Carinaria, Atlanta. 
ORDER III. GASTEROPODA. 
Animals which creep by means of a muscular disc situated under the 
body. 
SUB-ORDER I. APNEUSTA. 
Without distinct respiratory organs, and without a shell. 
Famity: ANANGIA. 
Genera: Rhodope, Pelta, Actaeon, Actaeonia, Lissosoma, Chalidis, Flabel- 
lina, Zephyrina, Amphorina. 
Famity: AnaropHora. 
Genera: Tergipes, Venilia (Proctonotus), Calliopoea, Eolidina, Aeolis 
" (Eolidia). 
SUB-ORDER I. HETEROBRANCHIA. 
The branchiae inserted more or less freely upon various parts of the 
‘body. Sometimes there is a very simple patelliform shell. 
Famity: Nouprprancuza. 
Genera: Scyllaea, Tritonia, Thetis, Doris, Polycera, Plocamophorus. 
Famity: Inreroprancuta. 
Genera: Diphyllidia, Phyllidia, Ancylus. 
Famity: CYcLOBRANCHIA. 
Genera: Patella, Chiton. 
Famity: Scurrprancuta. 
Genera: Haliotis, Fissurella, Emarginula. 
